Set the time according to the current time zone
#include <time.h> void tzset( void );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The tzset() function sets the global variables daylight, timezone and tzname according to the value of the TZ environment variable, or to the value of the _CS_TIMEZONE configuration string if TZ isn't set, or to UTC0 if neither is set.
The global variables have the following values after tzset() is executed:
The time that you set on the computer with the date command reflects Coordinated Universal Time (UTC). The environment variable TZ is used to establish the local time zone. For more information, see “Setting the time zone” in the Configuring Your Environment chapter of the Neutrino User's Guide.
#include <stdio.h> #include <stdlib.h> #include <time.h> void print_zone() { char *tz; printf( "TZ: %s\n", (tz = getenv( "TZ" )) ? tz : "default EST5EDT" ); printf( " daylight: %d\n", daylight ); printf( " timezone: %ld\n", timezone ); printf( " time zone names: %s %s\n", tzname[0], tzname[1] ); } int main( void ) { tzset(); print_zone(); setenv( "TZ", "PST8PDT", 1 ); tzset(); print_zone(); return EXIT_SUCCESS; }
produces the output:
TZ: default EST5EDT daylight: 1 timezone: 18000 time zone names: EST EDT TZ: PST8PDT daylight: 1 timezone: 28800 time zone names: PST PDT
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |
ctime(), daylight, localtime(), localtime_r(), mktime(), strftime() timezone, tzname
“Setting the time zone” in the Configuring Your Environment chapter of the Neutrino User's Guide